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Witnessed only seven times since the time of Galileo, Venus’s
solar crossing on Tuesday (June 5) is a rare and historic event
that shouldn’t be missed. Unless modern science discovers a way
to delay or halt the aging process, this will be the last Venus
transit we’ll ever get to see in our lifetime — the next transit
won’t take place until 2117, or 105 years from now.

The
transit of Venus in 2012 will begin at about 3:09 p.m. PDT
(6:09 p.m. EDT or 2209 GMT) and last nearly seven hours as Venus
crosses the face of the sun, according to NASA. Observers on
seven continents, including part of Antarctica, will be able to
see the Venus transit, though for some skywatchers the event will
occur on Wednesday, June 6, due to the International Date Line.

But how can
Venus transit photographers capture the rare celestial sight
safely? The basic requirements for photographing the transit with
a digital camera are very much the same as those for imaging
sunspots or a partial solar eclipse. And as luck would have
it, these same tips can help you snap photos of a
partial lunar eclipse of Monday (June 4), too!

Here are things to keep in mind when shooting this
much-anticipated celestial alignment for posterity:

1. Filter! Filter! Filter!Protect your eyes and
equipment by using a proper, visually safe solar filter to cut
down the sun’s intense brightness and heat. Use a No. 14 welder’s
glass filter or purchase special solar filters — made of
aluminized polyester or black polymer film or metal-coated glass
or resin — from reputable dealers such as Thousand Oaks,
Astro-Physics, Kendrick Astro Instruments, and Orion Telescopes
& Binoculars. Make sure the filter is securely mounted on the
front of your telephoto lens or telescope.

Color-negative or slide film, smoked glass, ordinary sunglasses,
Mylar balloons, space blankets, black plastic trash bags, CDs,
and polarizing or neutral-density (ND) filters used in regular
photography are considered not safe for solar viewing, and
therefore should not be used. [ How
to Safely Photograph the Venus Transit (Photo Guide) ]

2.Use a telescope or telephoto
lens: Decide what you want to record — the whole disk of
the sun with the tiny pitch-black silhouette of
Venus in it or close-ups of the ingress (entry) or egress
(exit) of Venus’ disk along the edge of the sun to try and record
the so-called “black-drop” effect. In this elusive phenomenon,
first reported by astronomers during the transit in 1761, as
Venus’s silhouette makes contact with the solar disk’s edge,
Venus’s outline seems to get distorted into a teardrop shape.

To produce a reasonably large image of the sun with a digital
camera, you’ll need a telephoto lens or telescope with a focal
length of 500 to 1,000 millimeters, or even longer. You’ll also
need a tripod or mounting that is beefy enough to carry the load.

You can boost the magnification of your telephoto lens using a 2x
teleconverter. For the telescope, try magnifying the image with
an eyepiece or Barlow lens.

3. Check your focus: Focusing is especially
critical when you use a
telescope or long telephoto lens that doesn’t have a fixed
“infinity” setting. Don’t rely on the camera’s auto-focus
function; switch to manual (M) mode instead and use the edge of
the sun or nearby sunspots for focusing. Once you achieve
sharpest focus, tape down your lens’s focus ring (or lock the
telescope focuser) to prevent it from accidentally being moved
during the transit. Be sure to recheck your focus as the transit
progresses since daytime heating can cause the focus to shift
slightly. If needed, wrap a space blanket around your gear to
keep it cool.

4. Shoot at high resolution: A digital
camera’s image quality and resolution is determined by the number
of pixels in its sensor (expressed in millions of pixels, or
megapixels). The more pixels the camera has, the better the
quality of the image will be. To take full advantage of the
camera’s capability, shoot images using high-resolution formats
such as the highest-quality JPEG or uncompressed TIFF or RAW
files. This will allow you to make 8 x 10, 11 x 14, or larger,
prints while retaining the images’ overall sharpness and smooth
tones. [Venus
Transit of 2004: 51 Amazing Photos]

5. “Bracket” your exposures: You can either
use the camera’s auto-exposure mode or manual (M) mode to
determine your exposure settings. If you prefer to do it
manually, try various combinations of shutter speed, f/stop, and
ISO speed — a technique known as “bracketing” — and see which
ones would come out best and use that as a guide. Don’t be afraid
to experiment.

To capture the moment of ingress and/or egress, switch your
camera to continuous shooting or “burst” mode so it can take many
shots in quick succession. Be sure to test your equipment and
practice your procedure ahead of the transit. Try to do your
testing around the same time of day the transit will occur to
determine the best exposure to use.

6. Try to minimize vibrations: The slapping of
the viewfinder mirror in DSLR cameras can cause blurry images,
especially at slow shutter speeds. To reduce camera jitter,
operate the shutter button with a long mechanical or electronic
cable release, or use the camera’s delay timer. If possible, lock
the viewfinder mirror up before each exposure (consult your
camera manual on how to do this). Use an ISO setting of 400 or
800 to keep your exposures short. [Amazing
Video of the 2004 Venus Transit]

Choose an observing site that is far from vehicular or pedestrian
traffic and is sheltered from the wind. A geared head or fluid
head on a tripod can eliminate jerky movements and make it easier
to manually follow the sun as it moves slowly across the sky. To
improve the tripod’s stability, hang your backpack, camera bag,
water jug or other weights under its center post. You can also
place rubberized footpads or mats under each tripod leg to absorb
ground or wind vibrations.

7. Bring spare batteries and memory cards: On
Venus
transit day, be sure to use a fully charged battery. Keep a
spare one as backup since the event can last for an hour or more,
depending on your location. (In Hawaii and Alaska, the transit
will last approximately 6 hours 40 minutes from start to finish.)

Digital cameras can be power hogs, especially if you use the LCD
screen constantly. If your camera has an AC power adapter and
there’s a wall outlet nearby, use them so you don’t have to worry
about depleting your battery during the transit.

High-resolution images take up a lot of memory so use fast,
large-capacity storage cards (4 to 8 gigabytes, or more) to avoid
running out of memory at a critical time.

8. Shoot the transit in
hydrogen-alpha: Specialized hydrogen-alpha
telescopes, such as the Coronado PST and SolarMax II series from
Meade Instruments, provide
stunning details on the sun, which make for a dramatic
backdrop to Venus’ disk.

Unlike ordinary, unfiltered light from the sun, also known as
“white light,” H-alpha is the red light emitted by hydrogen atoms
in the sun’s atmosphere, called the chromosphere, at a wavelength
of 656.3 nanometers. If there are large solar prominences along
the edges of the sun, it might be possible to glimpse Venus
against a prominence right before the planet’s disk enters, and
right after it leaves, the sun’s disk.

9. Shoot with video: As with digital cameras,
you’ll need a proper solar filter over the camcorder’s lens. Many
camcorders have zoom lenses with up to 40x or more optical
magnification. To videotape the transit, simply mount the
solar-filtered camcorder on a tripod, aim it at the sun and zoom
in to its highest power. Use the camcorder’s manual settings, if
available, to prevent the sun’s image from getting overexposed.
Take short clips every five minutes or so to create a short
time-lapse movie
of the Venus transit.

High-end DSLRs as well as smartphones are also capable to
shooting still shots or HD videos of the transit through a
solar-filtered telescope.

10. Check the latest weather forecast: Get the
latest weather update from websites such as the National Weather
Service, AccuWeather, The Weather Channel or Weather Underground.
You can also view the latest weather images and animations from
NOAA’s GOES satellites to
help you plan on where to go in case clouds or rain showers
threaten
your intended Venus transit observing site.

After the transit, be sure to backup all your still images and/or
videos right away on DVDs, flash drives or your laptop’s hard
drive so you don’t lose any of your precious mementos.

A partial lunar eclipse takes place when the full moon passes
through the dark central part of Earth’s shadow, called the
umbra, and gets partly covered by the umbra.

Observers in eastern Australia and the Pacific will have a
ringside view of the entire two-hour-long eclipse. They will see
the moon immersed more than a third of the way (37 percent) into
the umbra at maximum eclipse. [ Lunar
Eclipse of June 4: Observer's Guide (Images) ]

Most of North and South America will see the moon set before the
eclipse ends; eastern Asia will miss the start of the eclipse
since it occurs before the moon rises.

In northeastern United States and eastern Canada, no part of the
umbral eclipse will be visible since the event starts after the
Moon had set. Western Canada and the U.S. West Coast offer the
next-best views — the moon doesn’t set there until after
mid-eclipse.

You can use the same transit setup and technique to photograph
the partial lunar eclipse, minus the solar filter, of course. You
will not see anything if you leave the solar filter on! Be sure
to put it back on before you shoot the transit the following day.

Good luck and clear skies!

Veteran astrophotographers and transitophiles Imelda Joson
and Edwin Aguirre are planning to capture the transit from
Southern California as the sun sets over the Pacific.